Question: $ { {-3} \times \left[\begin{array}{rr}{-2} & {1} \\ {4} & {-1} \\ {1} & {4}\end{array}\right] = {?} } $
To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-3}\times{-2} & {-3}\times{1} \\ {-3}\times{4} & {-3}\times{-1} \\ {-3}\times{1} & {-3}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{6} & {-3} \\ {-12} & {3} \\ {-3} & {-12}\end{array}\right]}$